Method and apparatus for percutaneously accessing an implanted port

ABSTRACT

Methods and apparatus for percutaneously accessing an implanted port use a large bore coring needle. The coring needle is periodically introduced to an aperture on the implanted port so that the needle passes through the same tissue tract. It has been found that repeated passage of the needle through the same tissue tract reduces patient trauma, with minimized bleeding, reduction in sensitivity, in contrast to the use of non-coring needles.

The present invention is a continuation-in-part of provisionalApplication Serial No. 60/036,124, filed on Jan. 21, 1997, and ofapplication Ser. No. 08/856,641 (Attorney Docket No. 17742-001700),filed on May 15, 1997.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to the design and use of medicaldevices. More particularly, the present invention relates to a methodand apparatus for accessing an implanted port.

Access to a patient's vascular system can be established by a variety oftemporary and permanently implanted devices. Most simply, temporaryaccess can be provided by the direct percutaneous introduction of aneedle through the patient's skin and into a blood vessel. While such adirect approach is relatively simple and suitable for applications, suchas intravenous feeding, intravenous drug delivery, and otherapplications which are limited in time, they are not suitable forhemodialysis and other extracorporeal procedures that must be repeatedperiodically, often for the lifetime of the patient.

For long-term vascular access suitable for hemodialysis, hemofiltration,and the like, the most common approach is to create a subcutaneousarteriovenous (A-V) fistula. The fistula is preferably created byanastomosing an artery, usually the radial artery, to a vein, usuallythe cephalic vein. The vein dilates and eventually arterializes,becoming suitable for repeated puncture using a needle for access. A-Vfistulas may also be created using autologous or heterologous veins, byimplanting synthetic blood vessels, typically PTFE tubes, and the like.

The needles used for percutaneously accessing an A-V fistula are largebore coring needles, often referred to as fistula needles. The needleshave a bore diameter of 1.49 mm or larger, and permit the high bloodflow rates needed for hemodialysis, hemofiltration, and otherextracorporeal procedures. One technique for repeatedly accessing an A-Vfistula is referred to as the "button hole" technique. Such techniquerelies on repeatedly accessing the fistula through the same tissuetract, eventually creating a non-healing channel through the tissueoverlying the fistula. The channel is lined with scar tissue which formsover time. While generally successful, the button hole technique resultsin significant bleeding everytime the fistula needle is removed after atreatment is completed. The bleeding, in turn, causes scabbing, and thescab must be removed prior to subsequent needle insertion in order toavoid the risk of pushing scab into the fistula. The removal of the scabcauses patient discomfort and bleeding and increases the risk ofinfection.

As an alternative to the use of an A-V fistula, a variety of implantableports have been proposed over the years for use in hemodialysis,hemofiltration, and other extracorporeal treatments. Typically, the portincludes a chamber having an access region, such as a septum, where thechamber is attached to an implanted cannula which in turn is secured toa blood vessel. In the case of veins, the cannula is typicallyindwelling, and in the case of arteries, the cannula may be attached byconventional surgical technique.

Percutaneous access to a port through a septum, however, is generallylimited to small diameter, non-coring needles. Large diameter needleswill core the septum, i.e. form permanent channels therethrough, whichwill destroy the septum after repeated uses. Small diameter, non-coringneedles will remove little or no material from the septum, allowing itto close after the needle is removed. While small needles will thuspreserve the septum, they are generally incompatible with the high flowrates which are used with hemodialysis and other extracorporealtreatments.

Implantable ports having an access aperture and internal valve mechanismfor isolating the implanted cannula have also been proposed. One type ofimplantable valved port is described in a series of issued of U.S.patents which name William Ensminger as inventor. The Ensminger accessports have internal lumens for receiving a percutaneously introducedneedle and an internal valve structure for isolating the port from anassociated implanted cannula. Generally, the Ensminger ports have aneedle-receiving aperture which is oriented at an inclined anglerelative to the patient's skin. The Ensminger patents do not describeport access using large diameter, coring needles, such as fistulaneedles. Moreover, as many of the specific Ensminger designs employelastomeric valve elements, it is likely that the valve mechanisms wouldbe damaged if the ports were accessed by a fistula needle or other largebore coring needle. Representative Ensminger patents are listed in theDescription of the Background Art below.

For these reasons, it would be desirable to provide improved methods andapparatus for percutaneously accessing subcutaneously implanted ports.Such methods should reduce patient trauma, provide for reliable accessto the implanted port, minimize the risk of infection to the patient,and preferably require only minor modifications to present portimplantation procedures. In particular, it would be desirable to providemethods and apparatus for establishing high volume access tosubcutaneously implanted ports having valve mechanisms, using largediameter needles, such as conventional fistula needles. Suchpercutaneous access should accommodate repeated needle penetrationsthrough the same tissue location overlying an aperture of the accessport. At least some of these objectives will be met by the inventiondescribed hereinafter.

2. Description of the Background Art

U.S. Pat. No. 5,562,617 and WO 95/19200, assigned to the assignee of thepresent application, describe implantable vascular access systemscomprising an access port having an internal slit or duck bill valve forpreventing back flow into the port. Vascular access ports having variousarticulating valves for isolating the port from the vascular system inthe absence of external percutaneous connection to the port aredescribed in the following U.S. patents which name William Ensminger asan inventor: 5,527,278; 5,527,277; 5,520,643; 5,503,630; 5,476,451;5,417,656; 5,350,360; 5,281,199; 5,263,930; 5,226,879; 5,180,365;5,057,084; and 5,053,013. Other patents and published applications whichshow implantable ports having valve structures opened by insertion of aneedle include U.S. Pat. Nos. 4,569,675; 4,534,759; 4,181,132 and WO96/31246.

SUMMARY OF THE INVENTION

The present invention provides improved methods, apparatus, and kits forestablishing access to subcutaneously implanted ports for a variety ofpurposes, including hemodialysis, hemofiltration, hemodiafiltration,apheresis, peritoneal dialysis, drug delivery, and the like. The methodsrely at least partly on the surprising discovery that repeatedpercutaneous penetrations with an access needle, even a large borediameter coring needle, to a subcutaneously implanted, valved accessport result in a tissue tract which has minimum bleeding after theneedle is removed, which rapidly heals even when accessed multiple timesin a single day, and which minimizes patient trauma as the tissue tractloses its nerve sensitivity over time. The tissue tracts which resultfrom accessing such implanted ports differ substantially from thosewhich result from accessing an A-V fistula using the so-called "buttonhole" technique, even when using identical fistula needles. Inparticular, the tissue tracts of the present invention do not result inthe tunnel ("button hole") which is developed over time with fistulaaccess. It is believed that this difference results at least partly fromthe ability of the valved port to inhibit bleeding back into the tissuetract when the needle is withdrawn. Inhibition of back bleeding lessensor eliminates scab formation over the penetration point. As discussedabove, elimination of the scab obviates the need to remove the scabbefore the next needle penetration which may occur as soon as severalhours later. The ability to eliminate or lessen scab removal is asignificant benefit to the patient. In addition, by utilizing thepreferred access ports of the present invention, the tissue tract may beformed vertically, thus lessening its length and further reducingbleeding and patient trauma. The access port is also particularly easyto locate beneath the skin, and when combined with the ability tovertically introduce the needle, targeting of the port is greatlysimplified. The ability to accurately and simply target the port lessensthe chance that the needle will be misdirected, still further reducingpatient trauma and enhancing the unique tissue tract formation whichunderlies the present invention.

According to the present invention, a method for percutaneouslyaccessing an implanted port in a patient comprises providing a needle,typically a coring needle having a bore size of at least 1.16 mm (16 G),preferably being at least 1.33 mm (15 G), more preferably being at least1.55 mm (14 G), even more preferably being at least 1.73 mm (13 G), andstill more preferably being at least 2.08 mm (12 G). The needle isaligned with an aperture on the port, where the port is subcutaneouslyconnected to a blood vessel and the port comprises a valve whichselectively isolates the port from the blood vessel. In preferredaspects, the needle is introduced vertically and the valve will openupon insertion of the coring needle into the aperture and will closeupon withdrawal of the needle from the aperture. After alignment, thecoring needle is percutaneously introduced through tissue overlying theport and into the aperture. The needle will open a blood flow pathbetween the blood vessel and the port.

In another preferred aspect of the method of the present invention,blood is flowed between the blood vessel and a catheter attached to theneedle through the port. The needle is then withdrawn from the apertureon the port, and the valve closes to inhibit bleeding from the bloodvessel to the tissue tract which was created by the needle. It is stillfurther preferred to subsequently provide another needle, preferably acoring needle having a bore size of at least 1.16 mm. The other needleis then aligned with the aperture on the port and percutaneously(preferably vertically) introduced to the port through the same (atleast partially healed) tissue tract which was created by the earlierneedle penetration(s). Blood is then flowed between the blood vessel andthe catheter (via the port, connecting cannula, etc.) attached to theother needle through the port, and the other needle subsequentlywithdrawn from the port.

Such repeated needle penetrations will be performed periodically,typically at intervals as short as two hours to as long as four days,usually from four hours to two days. Usually, the coring needle will beintroduced in a direction which is generally normal or perpendicular tothe skin surface through which it is being introduced, with the repeatedaccess steps eventually creating the nerve depleted tissue tractdescribed above.

The present invention still further provides kits comprising a coringneedle having a bore size of at least about 1.16 mm (16 G), such as afistula needle. The kit further comprises instructions for use settingforth any of the methods described above. The needle and theinstructions for use are packaged together, where the instructions maybe on a separate instruction sheet and/or may be provided on a portionof the packaging. Usually, the coring needle will be part of a catheter,where the needle is connected or connectable to the catheter to providea flow path through the needle and into a lumen of the catheter.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a first embodiment of an access catheterhaving a large diameter coring needle suitable for use in the methodsand kits of the present invention.

FIG. 2 is a detailed view of the distal end of the catheter of FIG. 1,showing the access needle in cross-section.

FIG. 3 is a detailed view of an alternative distal end of the catheterof FIG. 1, showing the access needle in cross-section.

FIGS. 4A-4D illustrate use of the access needle and catheter of FIGS.1-3 for accessing a subcutaneously implanted port according to themethod of the present invention.

FIG. 5 illustrates a kit according to the present invention comprising alarge bore coring needle, a package, and instructions for use.

DESCRIPTION OF THE SPECIFIC EMBODIMENTS

The methods and apparatus of the present invention for creating apercutaneous access tract are useful with virtually any type ofimplantable access port having an aperture capable of receiving aneedle, preferably a large bore coring access needle. It is furtherpreferred to utilize the methods of the present invention withimplantable ports having one, two, three, or more, discrete access portswhich may be vertically aligned with the access tract to bepercutaneously formed through overlying tissue. Such access tracts willbe useful for repeated access to the aperture, where the aperturedefines a specific target site through the overlying tissue.

The preferred access ports will have at least one aperture whichremovably receives the access needle, preferably in a verticalorientation in order to minimize distance of the tissue tract. Theaccess port will preferably be capable of immobilizing the access needlewhile the blood is being transferred through the port. Exemplary accessports are described in co-pending application Ser. No. 60/036,124, whichhas previously been incorporated herein by reference. Typically, theport will be implanted beneath the skin by a distance in the range fromabout 3 mm to 20 mm, usually from 5 mm to 15 mm.

Preferably, the present invention utilizes large bore coring needles,such as conventional fistula needles. By "coring needles," it is meantthat the distal tip of the needle will be sharpened and will be open ina forwardly direction so that the needle is capable of cutting tissue(and coring septums) as it is advanced therethrough in a forwardlydirection. Less preferred for use in the present invention are needleshaving a non-coring design, such as Huber needles which have aside-facing distal opening as well as stylets, etc. The preferredneedles will have a bore size of at least 1.16 mm (16 G), usually atleast 1.33 mm (15 G), more usually at least 1.55 mm (14 G), still moreusually at least 1.73 mm (13 G), and sometimes as large as 2.08 mm (12G), or larger. The needles may be composed of any conventional needlematerial, typically being a stainless steel, but could also be hardplastic.

Referring now to FIGS. 1 and 2, an access catheter 10 incorporating alarge bore coring needle 20 in accordance with the principles of thepresent invention will be described. The catheter 10 comprises acatheter body 12 having a proximal end 14 and a distal end 16. Thecatheter body 12 will typically comprise a flexible polymer tube,composed of a medically compatible organic polymer, such aspolyvinylchloride, and having a length in the range from 10 cm to 30 cm,preferably from 12 cm to 18 cm, and a lumenal diameter in the range from1 mm to 5 mm, usually from 3.4 mm to 4.6 mm. Such polymeric tubes may beformed by extrusion and will typically include a single lumen extendingthe entire length from the proximal end 14 to the distal end 16.

Fitting 18 is secured to the distal end of catheter body 12, typicallyby an adhesive, heat welding, solvent bonding, penetrating fasteners(not shown), or other conventional means. The fitting is shown as agenerally flat disk but could have a variety of alternative geometries.The access tube 20 is secured to the distally forward face of the disk,and the lumen of the needle is fluidly coupled to and aligned with thelumen of catheter body 12. An orifice 25 is disposed in the disk 18 andgenerally aligned between the lumen 21 of the needle, thus opening intolumen 27 in the catheter body. Usually, a connector 26, such as a luerconnector, is provided at the proximal end 14 of the catheter body 12.Such a connector, however, is not necessary and it is possible todirectly connect the catheter body to a desired treatment device, fluidsource, or other external apparatus.

As described in detail in co-pending Application, a compressible element30 is attached at the distal end 16 of the catheter body 12. Preferably,the compressible element is coaxially disposed about the proximal end ofneedle 20. The compressible element 30 may be impregnated with anantiseptic, antibiotic, or other active agent, which can be delivered tothe skin's surface as the needle 20 is penetrated therethrough. Such acompressible element, although generally preferred for use incombination with the needles of the present invention, does not formpart of the present invention.

Referring now to FIG. 3, an alternative configuration 16' of the distalend of the catheter 10 orients the access needle 20 at an approximatelyright angle (90°) relative to the distal end of the catheter body 12.The fitting 18 includes cap 32 which defines the 90° bend with an inlet34 receiving the distal end of the catheter body 12 and an outlet 36connected to the fitting 18. The catheter body 12 can extend through theinternal passage of cap 32 or, alternatively, may be secured at theinlet end. In either case, the substantially continuous lumen 27 iscreated through the catheter body to the orifice 25 and fitting 18 andthus to the lumen 21 of access needle 20.

Referring now to FIGS. 4A-4D, use of the catheter 10 having the distalend 16' (FIG. 3) and access needle 20 for accessing an implanted port Pwill be described. The port P will have an aperture A which ispreferably oriented to receive a vertically aligned needle. That is, theaccess needle 20 will preferably be percutaneously introduced throughthe skin surface S in a direction which is normal to or perpendicular tothe plane of the skin at the point where the needle is being introduced.After entering the port P, the access needle 20 will actuate an internalvalve (not shown) to open a flow path with a lumen and cannula C, wherethe cannula may be connected to a blood vessel or other body lumen orcavity, as described in detail in co-pending Application. The accessneedle 20 may be aligned over the aperture A by manually feeling the topof the port P. The port P is generally symmetric with the aperturepositioned in the center of the port. The user can feel the periphery ofthe port P and visually determine its center. The needle 20 is thenvertically penetrated through the skin and into the aperture, as shownin FIG. 4B. The thickness of tissue T overlying the aperture isgenerally from 3 mm to 15 mm, as described above.

The needle 20 will be left in place in port P while the desiredprocedure, such as hemodialysis, hemofiltration, peritoneal dialysis, orother procedure, is performed and completed. After completion of theprocedure, the needle 20 will be withdrawn, as illustrated in FIG. 4C.Withdrawal of the needle will leave a tissue tract TT through the tissueT overlying the port P. Because the internal valve of port P will haveclosed, bleeding from the body lumen, typically a blood vessel, will beinhibited. Both the vertical orientation of needle entry and theinhibition of back bleeding into the tissue tract which is left afterwithdrawal of the needle contribute to the lessening or elimination ofscab formation and reduction in patient trauma and rapid healing in anon-fibrous manner. Surprisingly, such benefits may be achieved evenwhen using the preferred large bore access needles described above. Therapid healing and minimum trauma have been found even when the port isaccessed as many as four times per day. Such a result could not havebeen predicted prior to the present invention and provides substantialadvantages over the use of the non-coring needles typically used withimplanted ports.

The tissue tract remaining after withdrawal of the catheter, as shown inFIG. 4C, is ready to receive a second catheter as shown in FIG. 4Dvirtually immediately after the first catheter is withdrawn. Typically,additional access needles 20 and associated catheters will be introducedover periods of from two hours to four days, usually from four hours totwo days. Such cycle times are suitable for performing a wide variety ofchronic procedures, such as hemodialysis, hemofiltration, peritonealdialysis, and the like.

Referring now to FIG. 5, a needle 50, typically a large bore coringneedle, according to the present invention, may be packaged togetherwith instructions for use (IFU) in a kit, as shown in FIG. 5. Aconventional package which may be a pouch 52 or any other suitablepackage, such as a tray, box, tube, or the like, may be used to containthe needle 50 and the IFU, where the IFU may be printed on a separatesheet and/or may be printed on the packaging itself. Optionally, but notnecessarily, the needle may be sterilized within the package, e.g. byradiation or ethyleneoxide. The instructions may set forth any of theaspects of the method of the present invention described above.

While the above is a complete description of the preferred embodimentsof the invention, various alternatives, modifications, and equivalentsmay be used. Therefore, the above description should not be taken aslimiting the scope of the invention which is defined by the appendedclaims.

What is claimed is:
 1. A method for percutaneously accessing animplanted port in a patient, said method comprising:(a) providing aneedle; (b) aligning the needle with an aperture on the port, whereinthe port is subcutaneously connected to a blood vessel and contains avalve which isolates the aperture from the blood vessel; (c)percutaneously introducing the needle through tissue overlying the portand into the aperture, wherein the needle opens a blood flow pathbetween the blood vessel and the port; (d) flowing blood between theblood vessel and a catheter attached to the needle through the port; and(e) withdrawing the needle from the aperture, wherein the valve closesto inhibit bleeding from the blood vessel to a tissue tract created bythe needle; (f) providing another needle; (g) aligning the other needlewith the aperture on the port; (h) percutaneously introducing the otherneedle through the same tissue tract into the aperture, wherein theneedle opens a blood flow path between the blood vessel and the port;(i) flowing blood between the blood vessel and a catheter attached tothe other needle through the port; and (j) withdrawing the other needlefrom the aperture, wherein the valve closes to inhibit bleeding from theblood vessel to a tissue tract created by the needle.
 2. A method as inclaim 1, wherein the needle has a bore size of at least 1.16 mm.
 3. Amethod as in claim 1, wherein the other needle has a bore size of atleast 1.16 mm.
 4. A method as in claim 1, wherein the steps (g) through(j) are performed from two hours to four days after step (e).
 5. Amethod as in claim 1, further comprising repeating steps (f) through (j)periodically.
 6. A method as in claim 5, wherein the steps (f) through(j) are repeated every two hours to every four days.
 7. A method as inclaim 1, wherein the needles are introduced in a direction generallynormal to the skin surface at the point through which it passes.
 8. Akit comprising:a needle; instructions for use setting forth the methodof claim 1; and a package containing the port and instructions.
 9. A kitas in claim 8, further comprising a catheter connected or connectable tothe needle.